Manufacture of lubricating oils



Apria 29, 1930.,

E. c. HERTHEL ETy Al.

l MANUFACTURE OF LUBRICATING OILS Filed June 16. 1928 ATTORNEYS .Patented Apr. 29, i930I .UNITED s.1-ArEs PATENT OFFICE:

EUGENE c. HEBTHEI., or cHIcAGo', ILLINOIS, AND HARRY I.. PELzEn, or IIIGfzlaILANIJ, INDIANA, AssIoNoEs 'ro sINcLAIE EEFINING coMPANY, or NEW Youn, N. Y., L

CORPORATION OF v M ANUFACTUBE .0F LUBRIGATING OILS .Ippnqation mea :une is, 192s. serial* No. 285,820.

This invention relates to improvements in the manufacture of distilled lubricating oils j from petroleum. stocks. The invention is of: special value and application in the manufacture of distilled lubricating oils from certain types of crude oils or crude oil stocks of which the Gulf coast, SouthTexas and the California oils maybe taken as exam les.

In general, lubricating oils may be de ed I as' oils heavier than gas oil, heavier than about B., and having viscositiesupwards l through the .hotf alkaline liquid oil bath are of about at 100 F. SayboltUniversal.

There is a group of constituents, apparently characteristic of naphthene base crude oils,

which are extremely objectionable as components of lubricating oils in particular. These constituents are particularly objectionable in that the render unstable lubricating oils in which thI them in other respects, color for example. As yet, this group `of objectionable constituents has not. been definitely identified. These objectionable constituents are themselves apparently ofrelatively low boiling point, yet they polymerize quite readily to forma tar or tar'rysubstance;4 This polymerization is promoted, for example, by the presence ofair or steam. With certaln types ofstocks, additional quantities of these objectionable constituents seem to be formed as j.

terial formlng the treatln long as the oil is maintained at elevated temperature', this effect increasing with temperature increase. f

A number of schemes of procedure have beenpropolsed intended to avoid the objectionable incidents of the presence of this group of objectionableconstituents in lubricating oils, but these proposals have not been entirely satisfactory; in some cases because of operating difficulties and in other cases because of failure to reach the real difficulty.

The present invention provides articularly an improved method of Separating constituents of the objectionable group. noted above from lubricating oil products produced from stocks containing these objectionable constituents, and the present invention is also useful in other applications, as will apipear, in providing an improved method of ey are present. They also impair the quality'lo'f Ilubricating oils containing the dlstilled lubricating oil products. The

treating lubricating-oil products with caustic alkali. i

According to the present invention, the petroleum. stock containin the lubricating oil constituents is subjecte to distillation and during the distillation the vapors forming the lubricatin oil products when condensed are 'bubbled t rough a" hot alkaline liquid oil `bathin whichy the. se

l j arated objectionable constltuents aregcollected and from which they are discharged-','ithe vapors after passage subjected toa relliixing operation from which refluxis.returned-:tothe bath, the temperature ofthe bath land the refiuxingoperation are controlled to maintain uncondensed the constituents forming the desiredv lubricating I oil products, and the vapors including the lubrioatlng oil constituents escaping from the reliuxing operation are condensed to form constituents of the raw stock suitable as. components of the desired lubricating oil products" are vaporiz'e'd from vthe raw stock and these vapors are bubbled through the hot `alkaline liquid oil bath the surface-thereof. he oil bath is maintained alkaline as the operation proceeds by supplying a caustic alkali thereto.` The confdensed lubricating oil products are not perby. introduction beneath merization of constituents of the objectionl able group noted above. Steam may with advantage besupplied to the treating bath plied also assists in this polymerization and in some cases also'seems to make the caustic alkali more active. In the refluxing operation, high boiling constituents not suitable as components of the lubricating oil products including reaction products ofthe hot alkaline treatment and the products of polymerization of any objectionable constituents presas a distillation medium, and when so supent are condensed and returned to the treating bath. from which they are discharged.

The vaporization of the raw petroleum stock may be effected in a shell still or a pipe still, for example. The vaporization may be carried out under pressures approximating atmospheric pressure or under sub-atmospheric pressure and with or without the introduction of steam or other hot gaseous medium reducing the partial pressure of the oil vapors. As applied to crude oils, the vapors subjected to the alkaline treatment of the invention may comprise the total vaporized fraction of the crude oil.

The treating bath is with advantage externally unheated. The formation of separating carbonaceous material in the bath may thus be avoided or minimized. Contact between the alkaline material of the bath and surfaces carrying a burden of heat transfer is also thus avoided. The hot oil bath is advantageously maintained of substantially constant volume. The volume of the bath may be controlled by regulating the temperature of the caustic alkali supplied thereto, by the introduction of steam or some heated gas, 'by the regulated discharge of liquid from the bath, or by refluxing to the bath heavier components of the vapors taken off therefrom. The caustic alkali is advantageously supplied to the treating bath by introduction with the vapors from the vapor- 'izing operation and in amount suiicient to maintain that excess of alkali in the bath required to neutralize completely the escaping vapors. y p

The vapors taken off from the treatment of the invention may be condensed or fractionally condensed in any convenient apparatus. These vapors may, for example, be passed through a series of towers in which progressively lighter fractions are condensed. l

As applied to crude oils, the vapors taken off from the hot oil bath may thus be condensed as a series of distillates, the heavier and more viscous fractions of the series constituting the lubricating oil products.

The invention will be further described in connection with the accompanying drawing which illustrates, diagrammatically and con-p. ventionally, one form of apparatus adapted, A

in conjunction with a suitable still and a suitable fractionating or condensing system, for

carrying out the invention. It will be understood that the invention can be carried out in other and different forms of apparatus; this particular form is illustrated merely for purposes of'exemplification. Any usual form of still and any usual ifractionating or condensing-system may be used in carrying out the invention and this part of the apparatus is, therefore, not illustrated.

Referring to the drawing, in the apparatus illustrated the vapors from the still are supplied through line 1 and are taken off, following' the treatment of the invention, through line 2 to the fractionating or condensing apparatus, the vapors passing from f line 1 through tower 3 to line 2. lThe tower4 VCooling coils 4 and 5 are provided in the dephlegmating section. Baiiles or trays for promoting vapor-liquid Contact and heat ex change are provided in the reiuxing sectlon.

A normally 'submerged inlet pipe 6 is provided in the treating section, connected to line l, for the introduction of the vapors from the still beneath the normal liquid level therein. Gauge 7 is provided for observation of the liquid level. Line 8 is provided for discharge of liquid from the lower end of the tower. Line 9 is provided for introduction of steam or other hot gaseous medium into the lower end of the tower beneath the normal liquid level therein. Line 10 is provided for introduction of caustic alkali with the vapors from line 1 through pipe 6.

In carrying out the invention in the apparatus illustrated,the lubricating oil vapors supplied through line 1 are bubbled though a hot alkaline liquid oil bath maintained in the lower section of tower 3, being introduced beneath the surface thereof through pipe' 6, this -tower 3, and the lubricating oil vapors are taken off through line 2 andseparately condensed. Components of the resulting condensate or condensates contact with the treating bath inthe lower section oftower 3 only' as vapors; the condensatelor condensates are not permitted to contact with the oily or tarry material forming this bath as such.

The following example will illustrate an operation embodying the invention, as carried out in apparatus of the typer illustrated: Gulf coast crude oil having an acid number of 1.85 is supplied to a small pipe still at a rate of about L100 gallons per hour and discharged from the pipe still at a temperature of about 800o F. After separation of unvaporized residual oil, the vaporized part of the stock is supplied through line 1 to the lower end of tower 3. An aqueous solution of caustic soda, 25 B., `is also supplied through line 10 to the lower end of tower 3 at a rate of about '5.5 gallons per hour. The temperature at the top of tower 3 is maintained in the neighborhood of G70-690 F.

^ and the temperature of the liquid bath in the coil 4 or coil 5 or both coils as required to maintain these temperatures. 4The l vapors escaping through line 2 from the upper end of tower 3 are fractionally condensed to form a heavy lubricating oil having an acid number of 0.042, la light lubricating oil having an acid number of 0.014, and a composite as oil and naphtha having an acid number o 0.014. A liquid bath of substantially constant volume is maintained in the lower end of the tower py regulated discharge of liquid through ine 8;

The tower 3, particularly the lower end, is with advantage lagged or thermally insulated and the liquid bath therein heated by the introduced oil vapors. Additional'heat may be supplied by the introduction of steam.

through line 9, steam superheated for eX- ample to SOO-900 F., or by the introduction of other hot gaseous media through line 9. The temperature of Athe caustic alkali as introduced through line `10 may also be regulated to assist in controlling the heat balance in the tower. The hot oil bath in the lower 4end of the tower 3l is maintainedat atemperceeds. Any tendency of the bath to decrease in volume may be counteracted by supplying the caustic alkali at a lower temperature, by cooling or increasing the cooling 'of the vapors in the upper end of the tower, by decreasing the rate of liquid discharge, or by decreasing the rate at whichy steam is supplied to the lower end of the tower if steam is used. Any tendency of the bath to increase in volume may be counteracted by supplying the caustic alkali at a higher temperature, by-'decreasing the vapors in the upper end of the tower, by increasing the rate of liquid discharge, or by supplying steam or increasing the supply of steam to the lower end of the tower. v l

Oil to be supplied to the vaporizing operation may be used as a cooling medium in the cooling coils 4 and 5, or some suitable external cooling medium may be soA used. The cooling may be controlled by regulating the rate of circulation of the cooling medium through the coils 4 and 5.

By introducing the `caustic alkali into-the vapors from the still before the latter enters the hot alkaline oil bath and then introduc-v ing the mixture into the body of the liquid bath as in the apparatus illustrated, a particularly eective contact between the oil vapors and the caustic alkali is obtained: The freshy liquid alkalineoil'bath' to which additional caustic alkali is continuously being added.

The inventionl is particularly adapted to continuous operation and the control aiorded by the invention is of special value .in maintaining uniform the distillate products over long periods of operation. The invention provides a articularly eiiective `contact between the lu ricating oil vapors and the caustic .alkali treating agent,-and in this respect 'also has the advanta e of economy in consumption of caustic al ali. By separation of residual unvaporized oil'from thevaporized components including the'lubricating oil before the latter are supplied to the treatment of the invention, the caustic tar or caustic residue produced may be kept separate from the major part of the residue and may be kept in buta minimum proportion o f the total residue produced in the com lete operation.

-Further, in the operation o the invention," difficulties due 'to' entrainment of reaction` products of' the 'alkaline vtreatment or' tarry oil bath by introduction beneath the surface thereof, mai'ntainin this oil bath alkaline by supplying caustic al ali thereto, discharging liquid from this bath, and taking ofi" from this oil bath the components of the lubricating oil in the vapor state and condensing the same without permittin acil:1 as such with t e liquid formingthe oil at a this condensate to con-` of petroleum stocks v l 2.111 the diseiuatiqn'of petroleum 'Stocks for the production oflubricating oils, theimprovcmentwhich comprises vaporizing from the Stock those constituents suitable as components of the' desired lubricating oil, passing the vapors containing these constituents through al hot liquid'il bath, maintained at substantially constant volume, by introduction beneath the surface thereof, maintaining this oil bath. alkalinev by supplying caustic alkali thereto, discharging liquid from this lbath, and taking olf from this oil bath the components of the lubricatingoil in the vapor state and condensing the same without permitting this condensate to contact as such with the liquid formingthe oil bath.

3. In the distillation of petroleum stocks l for the production of lubricating oils, the'improvement which comprises vaporizing from the stock those constituents suitable' as components of the desired lubricating oil, passing the vapors containing these constituents through a hot but externally unheated liquid oil bath by introduction beneath the surface thereof, maintaining this oil bath alkaline by supplying caustic alkalithereto, supplying steam to this oil bat-h, discharging liquid from 10 this bath, and taking off from this oil bath the 'components of the lubricating oil and condensing the same Without permitting this con-l densate to contact as such with the liquid forming the oil bath. l EUGENE C. HERTHE-L. HARRY L. PELZER. 

